Concrete recycling life cycle flows and performance from construction and demolition waste in Hanoi

Accepted Manuscript Concrete recycling life cycle flows and performance from construction and demolition waste in Hanoi

Simon Lockrey, Karli Verghese, Enda Crossin, Hung Nguyend PII:

S0959-6526(17)33265-1

DOI:

10.1016/j.jclepro.2017.12.271

Reference:

JCLP 11666

To appear in:

Journal of Cleaner Production

Received Date:

24 November 2016

Revised Date:

18 December 2017

Accepted Date:

30 December 2017

Please cite this article as: Simon Lockrey, Karli Verghese, Enda Crossin, Hung Nguyend, Concrete recycling life cycle flows and performance from construction and demolition waste in Hanoi, Journal of Cleaner Production (2017), doi: 10.1016/j.jclepro.2017.12.271

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT Concrete recycling life cycle flows and performance from construction and demolition waste in Hanoi Authors Simon Lockreya*, Associate Professor Karli Verghesea, Dr. Enda Crossinbc, Dr. Hung Nguyendd a

RMIT University, School of Architecture and Design. Building 100, Victoria St & Swanston Streets

Melbourne Victoria 3000, Australia. Email: [email protected] (Simon Lockrey). b

Swinburne University of Technology, Faculty of Science, Engineering and Technology, PO Box

3122, Hawthorn Victoria 3122, Australia. Email: [email protected] (Enda Crossin). c

RMIT University, School of Engineering. PO Box 71, Bundoora Victoria 3083, Australia. Email:

[email protected] (Enda Crossin). d

RMIT University, School of Business and Management, 521 Kim Ma, Ba Dinh District, Hanoi,

Vietnam. Email: [email protected] (Hung Nguyen). * Corresponding author. RMIT University, School of Architecture and Design. Building 100, Victoria St & Swanston Streets Melbourne Victoria 3000, Australia. Email: [email protected] (Simon Lockrey).

Abstract As construction increases through a rise in development in Vietnam, the environmental performance of recycling construction and demolition waste is not well documented. This paper addresses this lack of knowledge, by mapping the current recycling system and estimating recycling performance of a key component in construction and demolition waste in Vietnam, concrete. Primary data were collected directly from six Vietnamese construction enterprises involved in the life cycle of construction and demolition waste management. The results indicated that potential net environmental benefits exist for all impact categories examined if a mechanised plant were considered. Moreover, construction demolition waste may then be used for more permanent applications such as building foundations and in new building materials. The results confirm benefits to technological advancements in concrete recycling in the construction demolition waste sector. Fostering investment and interest in such strategies could be achieved by imposing clear and consistent construction demolition waste classifications, establishing clear lines of responsibility, and coordinating activities amongst key stakeholders to promote the benefits of concrete recycling. These findings consolidate the need of further research in Vietnam and other developing nations, where

ACCEPTED MANUSCRIPT more detailed life cycle inventory development and stakeholder engagement could help. Then better environmental outcomes through the concrete recycling management may be delivered. Keywords: Recycling, Vietnam, Concrete, Construction and Demolition, Life Cycle Assessment, Sustainability Abbreviations

AUPLCI - Australian Unit Process Life Cycle Inventory CO2 - Carbon dioxide C2H4 - Ethylene

C&DW - Construction and Demolition Waste ELCD - European data Life Cycle Database eq – equivalent IEA - International Energy Agency

ISO - International Organization for Standardization kg - kilogram km – kilometre LEED - Leadership in Energy and Environmental Design LCA - life cycle assessment LCI - life cycle inventory m3 - cubic metre NOx - Nitrogen oxides volatile organic compounds (VOCs), PANs - Peroxyacyl nitrates aldehydes PO4 - Phosphate

t - tonnes US - United States of America VGBC - Vietnam Green Building Council Words: 7,959 (without abstract, attributions, acknowledgements or abbreviation list)

ACCEPTED MANUSCRIPT 1

Introduction

Vietnam is in an upwards development trend, with construction activity forecast to increase by nearly 50% between 2013 to 2018 (AECOM, 2013). Despite the rapid growth of construction activity (AECOM, 2013), construction and demolition waste (C&DW) performance in Vietnam are not well documented. This opens an environmental conundrum as development escalates. Industrial recycling of C&DW into reusable products can be environmentally beneficial. The environmental benefits of utilising recycled C&DW is reflected by credits for recycling in green building certification schemes used in Vietnam, such as the US Green Building Council’s LEED (Leadership in Energy and Environmental Design) system, and Vietnam’s LOTUS system from the Vietnam Green Building Council (VGBC). It is anticipated that increased uptake of certification schemes could result in an increase in demand for better waste management and recycling of C&DW (VGBC, 2013). New and innovative materials (Mercader-Moyano et al., 2017), processes (Liu et al., 2017) and products may then result. Because recycling pathways are not well understood, it is not known if current informal recycling or potential future formal recycling, of C&DW in Vietnam would lead to environmental preferable outcomes. Life cycle assessment (LCA) serves as a tool which can be used to quantify environmental performance (Baumann and Tillman, 2004, Curran, 1993, Klöpffer, 1997, R. Heijungs et al., 1992). The data underpinning LCA are termed life cycle inventories (LCIs). LCA studies in Vietnam have typically relied on ad-hoc LCIs (Bosma et al., 2011, Huysveld et al., 2013, Kluts et al., 2012, Phong et al., 2011, Homäki et al., 2003), limiting the application of LCA in Vietnam more broadly. As such this paper aims to contribute a better understanding of C&DW in Vietnam by:  Understanding C&DW flows for a major metropolitan area, Hanoi, by tracking final flows to landfill and/ or recycling  Quantifying the environmental performance of C&DW recycling in Vietnam, through regionally relevant LCIs. This study addresses the lack of clarity, by identifying C&DW collection pathways for the major material in C&DW, specifically concrete, in Hanoi and then more broadly for Vietnam. This scope is limited to concrete due to its typical dominance in C&DW streams (Smith et al., 2011). Hanoi was used to identify current concrete waste management practices in a large

ACCEPTED MANUSCRIPT Vietnamese metropolis. Such a focus helped quantify environmental opportunities related to the current state of the recycling system, as Hanoi is a major centre of construction activity This research is also the first to utilise a streamlined LCA approach to estimate the environmental performance of Vietnam’s existing and potential concrete recycling systems. It is hoped that the contributions of this paper will lead to further research and action that will examine Vietnamese and other developing national C&DW recycling industries more broadly. The methodology used in the study could also serve as a basis to trace recycling performance in the future, at municipal, regional and national levels, for countries experiencing rapid urban development. The next section of the paper provides a review of literature on C&DW, and environmental benefits deriving from recycling through LCA. Comparative analyses on practices, pathways and environmental indicators can help facilitate the LCA modelling process, especially when there is a lack of concurrent practice and inventory data. This is the case in the Vietnamese context. Therefore Section 3 presents a methodological approach to consider practices, pathways and environmental indicators together. A number of results are developed by applying this methodology in Section 4, which culminates in a set of conclusions discussing implications for recycling practices and future research in Sections 5 and 6.

2

Vietnamese construction and demolition recycling

C&DW generated annually in Vietnam has increased from 1 million tonnes (t) in 2004 (Manowong and Brockmann, 2010) to 1.9 million t in 2011 (Kien et al., 2013). The focus on recovering waste in Vietnam is increasing (Thai, 2009). For instance recent national laws have been introduced, which are targeted at achieving a collective recycling rate of 30% by 2020 (Hotta, 2011). Despite this recycling target, it is apparent that an understanding of material flows and performance through recycling pathways for C&DW in Vietnam is limited. An understanding of informal small scale recycling of C&DW exists (World Bank et al., 2004), only at a local level (Waste Management and Environment Improvement Department, 2013). C&DW flows from major metropolitan centres are not well understood. An opportunity lies in remediating environmental impacts on a larger scale in these contexts. Infrastructure for C&DW recycling is also limited in Vietnam, with only one formal facility in operation (Kien et al., 2013). Apart from this limited capacity, the reasons for the limited C&DW recycling activity in Vietnam are not known. Potential reasons include the lack of

ACCEPTED MANUSCRIPT demand and/or economic viability (Manowong and Brockmann, 2010). A recent study showed that C&DW stakeholders in Hanoi viewed regulation, infrastructure, lack of education and logistical bottlenecks as main barriers to expand the recycling industry (Lockrey et al., 2016). This Hanoi experience mirrors other nations that have developed fast, such as China (Jin et al., 2017). The identification of C&DW stream material flows and performance within and between the informal and formal recycling systems would serve as a first step in understanding current recycling activities in Vietnam. Concrete generally dominates C&DW streams. For example, in 2008-2009, the Australian state of South Australia generated 1.8 million t of C&DW (Smith et al., 2011), a similar amount to Vietnam’s 1.9 million t in 2011 (Kien et al., 2013). Of that C&DW in South Australia, 89% was masonry material waste, which was dominated by bricks and concrete (Smith et al., 2011). Of the 1.8 million t, 67% in masonry materials was recovered. On a larger scale, the Australian state generating the most C&DW over the same period (New South Wales at 6.6 million t), 82% was masonry materials. Of the 6.6 million t, 67% in masonry materials was recovered. Both State’s recovery rates demonstrate the potential for recycling in Vietnam if the same attention were applied. Recycling can be treated as a process of waste management, and/ or material production. As such the process can alleviate both landfill constraints and virgin material production. Other environmental benefits may also exist, as Grant and James demonstrated in Australia in the recycling of C&DW types including bricks, plasterboard and soil/sand (Grant and James, 2005). Carre and Rouwette (2008) also used life cycle assessment in Australia to demonstrate greenhouse gas and solid waste reductions in recycling concrete into aggregate, relative to those of traditional aggregates produced from quarry stone. The net environmental benefit or burden of recycling in any of these contexts considers the resource use and emissions of recycling (e.g. due to collection and reprocessing activities) compared to avoiding the environmental intensity of landfill and virgin production of materials. Pathways, material flows and the environmental performance of C&DW management has been examined in Australia, Japan, Canada, Portugal, China and Malaysia (Tam et al., 2007, Hao et al., 2010, Hussin et al., 2013, Coelho and de Brito, 2013, Grant and James, 2005, Carre and Rouwette, 2008). However in Vietnam these aspects of the recycling system are not well understood. In light of this evidence, Vietnam deserves its own study on concrete recycling environmental performance, due to its unique political, social, economic and technological context (Ling and Nguyen, 2013). Indeed there is a lack of studies examining developing nations, particularly when urban C&DW levels are on a sharp rise. To

ACCEPTED MANUSCRIPT that end, this paper covers concrete Vietnamese C&DW pathways and material flows, as well as quantifying environmental performance. 2.1

Past LCA assessments of environmental benefits of recycling concrete

The reporting on the environmental performance of concrete typically focuses on the impacts of production, particularly with relation to the incorporation of recycled waste or recovered material (Crossin, 2012a, Crossin, 2015, Chen et al., 2010, Kurad et al., 2017). In contrast, the environmental performance of different waste management strategies for end-of-life concrete is not as well studied. Wu et al. (2014) report that compared to landfill, other waste management such as recycling, normally reduce greenhouse gas emissions. As part of a broad LCA into the environmental impacts of managing C&DW, Grant and James (2005) found a net environmental benefit associated with concrete. This outcome was driven by environmental credits from the production of material which could avoid the production of virgin steel and aggregate (Grant and James, 2005). In a more recent study, metals drove environmental benefits compared to aggregates when C&DW was considered (Wang et al., 2017). However, in this study aggregates still remained a waste issue in accounting for over 90% of the C&DW by mass. LCA outcomes of specific C&DW can also be sensitive to transport distances and types, as well as the processes used for recycling (Wang et al., 2017, Mercante et al., 2012, Marinković et al., 2010, Knoeri et al., 2013). The environmental indicators assessed in previous LCA studies vary, and include precursors to environmental impact, such as water use and sold waste generation; midpoint indicators of impact, such as photochemical oxidation potential and global warming potential; and endpoint indicators, such as human health (Chen et al., 2010). As such, using relevant indicators and LCA modelling derived from information from the Vietnamese context provides context specific visibility of the current state of play for C&DW. It also allows for potential alternatives to current C&DW scenarios to be compared, and if changes to practices and technologies make sense to implement.

3

Methodology

This study employs both secondary and empirical data to develop an LCA model for the Hanoi C&DW and recycling industry for concrete. This multi methods approach allowed for qualitative and quantitative data to be combined addressing the two major aims of this research. It also allowed for triangulation of key themes that developed in data analysis, and verification of the results across the methods (Woodside, 2010).

ACCEPTED MANUSCRIPT

To set up the LCA modelling, stakeholder interviews were used to evaluate the C&DW recycling system in Vietnam to reveal current practices and pathways (Brinkmann, 2018). The method for those interviews is detailed in Lockrey et al. (2016). The initial focus of interviews was on waste logistics, practices on construction sites, and concrete recycling versus quarry aggregate in the context of manual recycling, using electric tools, and a formalised recycling plant. In short, the interviews allowed better understanding of how recycling system operated. The general LCA method taken is further explained in Section 3.1, including elements from ISO 14040:2006 (International Organization for Standardization, 2006b) and ISO 14044:2006 (International Organization for Standardization, 2006b) that help to explain the approach taken. Section 3.2 develops measurement indicators and impact assessment for recycling and waste management. Section 3.3 establishes the LCA of Vietnamese C&DW.

3.1

LCA methodology

LCA is the process of evaluating the potential effects that a product, process or service has on the environment over the entire period of its life cycle (International Organization for Standardization, 2006b). The goal of using LCA for this part of the research was to assess the environmental benefit or burden of concrete recycling in Hanoi, Vietnam. Figure 1 illustrates the life cycle system concept of natural resources and energy entering the system with products, waste and emissions leaving the system. Raw materials (abiotic)

Raw materials

Material processing

Emissions to air

Raw materials (biotic)

Product manufacture

Energy resources

Distribution and storage

Emissions to water

Use

Disposal/ Recycling

Solid waste

Figure 1 - Life cycle system concept

The technical framework for LCA consists of four components, each having a very important role in the assessment. They are interrelated throughout the entire assessment and in accordance with the current terminology of the International Organisation for Standardisation (ISO). The four components are goal and scope definition, inventory analysis, impact

ACCEPTED MANUSCRIPT assessment and interpretation as illustrated in Figure 2.

Figure 2 - The framework for LCA from the International Organisation for Standardisation (2006b)

LCA has been used as the core method for determining the potential environmental impacts of the systems considered in this study. Individual subsystems within these systems, such as landfill waste processing present significant assessment challenges and are worthy of dedicated LCA studies in their own right. Therefore, to achieve the study aim, significant reliance upon secondary data sources (other LCA studies and environmental reports) was required in order to cover the system scope. In determining the benefits of concrete recycling a comparative model, similar to that used in Grant et al. (2001) was employed. The model was based upon the assumption that waste forwarded to recycling would otherwise end up in landfill. This assumption then governs a definition of recycling benefit which is equal to the impact of the recycling system, less the avoided impacts of the alternative system. The resulting definition of recycling benefit is as described in Figure 3. Recycling System Transport +

Sorting

+

Reprocess + Local

Alternative System

Landfill

-

Production Local

+ Transport +

Landfill

=

Net Outcome +ve Benefit, -ve Impact

Figure 3 - Definition of recycling benefit adapted from Grant et al. (2001)

ACCEPTED MANUSCRIPT The model used by Grant et al (2001) has informed several other waste LCA studies (Grant et al., 2001, Grant et al., 2003, Grant and James, 2005, Carre et al., 2009, Carre et al., 2015) and addresses the need to account for the impacts of business as usual, reprocessing of the waste material, and displacement of virgin material production. This approach may be valid, however alternative approaches exist. In determining the impacts of the existing system this way, a fundamentally attributional approach (the application and limits of which are detailed in Section 6) has been employed. An attributional approach then characterises impacts based on the existing systems operation.

3.1.1

Functional unit

The primary function of a concrete recycling system is to dispose of waste generated by the construction sector, measured by volume. A concrete recycling system also has an important secondary function as it generates reprocessed materials for use in other contexts. The functional unit for this study is therefore defined as: “The management of 1 cubic metre (m3) of recyclable concrete material discarded at a typical C&DW site in Hanoi, Vietnam”. In regard to the volumetric unit of measure of 1 m3, this equates to an average of 1.5 t of gravel or concrete (Alex Fraser, 2014, SImetric, 2014), which is applied to the inventory throughout the LCA to achieve a consistent measure of the contributing factors to impacts.

3.2

Impact Assessment Method

The impact assessment method used in this research is intended to provide sufficient information to assess the environmental impact of recycling concrete in Hanoi. The impact assessment method selected is a mid-point method to avoid the complexity, subjectivity and lack of transparency associated with end-point impact assessment methods. The impact indicators selected, and the rationale for inclusion of each, are described in Table . It is acknowledged that even the four indicators considered only represent a fraction of possible environmental impacts that could be caused by the systems studied. This is a limitation of the study.

ACCEPTED MANUSCRIPT Table 1 - Characterisation impact method Indicator

Description

Unit

Rationale for inclusion

Indicators of environmental impact Climate change effects resulting from Global

the emission of carbon dioxide (CO2),

warming

methane or other global warming gases into the atmosphere.

kilogram

Global warming is an issue

(kg) CO2

of international importance.

eq

Measurement of the increased potential

Waste treatment processes

of photochemical smog events due to

and transport involve the

the chemical reaction between sunlight Photochemical

and specific gases (including nitrogen

kg C2H4

oxidation

oxides (NOx), volatile organic

eq

compounds (VOCs), peroxyacyl nitrates

Waste treatment processes

Eutrophication is the release of nutrients

could contribute to the

(mainly phosphorous and nitrogen) into biotopes, and potentially causing oxygen

contribute to smog, an metropolitan areas.

into the atmosphere.

Eutrophication

air, many of which could important consideration in

(PANs), aldehydes and ozone) released

land and water systems, altering

emissions of chemicals to

pollution of waterways kg PO4 eq

directly through processes relating to organics

depletion effects such as increased algal

processing or their

growth.

alternatives.

Precursors to environmental impact Solid waste generation and

Net solid waste generated. Total of all Solid waste

solid waste generated by the processes considered.

kg

avoidance is provides guidance as to systemic recycling waste impacts.

Global warming, eutrophication, and photochemical oxidation could all be considered indicators of environmental impact. The remaining indicator solid waste is more correctly considered a pre-cursor indicator that may or may not indicate environmental impact. For example, solid waste quantifies waste being generated by a system; it does not reveal if that waste has had a detrimental impact on the environment. Therefore, the exact nature of the environmental impact is unknown. Photochemical oxidation and eutrophication tend to cause locally observable environmental impacts under certain conditions. Photochemical oxidation causes smog where transport activities are concentrated in urban areas, whereas impacts are unlikely to be observed if emissions occur in sparsely populated areas, such as at sea or

ACCEPTED MANUSCRIPT in rural areas. Eutrophication impacts are most pronounced when emissions are to waterways, or through atmospheric transmission to waterways. As the LCA for this study does not automatically consider these factors, interpretation of these indicators, in particular, needs to consider the likely type and location of the emission. To sum up, the indicators chosen in Table were selected to assess a range of issues that recycling would be likely to affect a Vietnamese context considering both local and global issues. 3.3

Establishing the LCA of concrete recycling from C&DW in Hanoi

This section provides a summary of the recycling (Section 3.3.1) and alternative system (Section Error! Reference source not found.) modelled for a LCA of concrete recycling from C&DW in Hanoi. The system boundary is described in Section 3.3.3. The life cycle inventory and impact assessment results are then presented in Section 4.2.1 and 4.2.2 respectively. 3.3.1

The recycling system

The recycling system under study consisted of processes needed to recover and reprocess concrete materials collected from C&DW sites. This system was modelled as both a current and future scenario. Reprocessing activities shown in Error! Reference source not found. have been simplified to allow for presentation on a single diagram. The current system of recycling uses manual crushing of concrete (sometimes with electric tools) into aggregate, with recovered materials used in aggregate applications such as temporary roads. These applications eventually see aggregate ending up in a landfill or loss to the biosphere through osmosis. The future system was defined as a mechanised (automated) concrete recycling plant, of which two options were modelled in Section 4.2.1. 3.3.2

The alternative system

The alternative system can be defined as a ‘shadow’ of the recycling system described above. As described by Figure 4 the study included unit processes sufficient to generate the same primary and secondary functions as the recycling systems under consideration, however by different means. In the alternative system, waste is disposed of to landfill and material (equivalent to those produced by the recycling system), namely gravels aggregate,

ACCEPTED MANUSCRIPT is produced from a virgin feedstock. In being described as such, the alternate system can also be equated to the current recycling system, in so much as concrete is generally crushed up (as per virgin aggregate), and then transported to be used in temporary applications like unsealed roads (as per virgin aggregate). It is then eventually disposed of to landfill or lost to the biosphere from the final function it was performing.

Recycling System (Current and future) Electricity generation and supply Natural gas extraction and supply

Waste disposal at C&D site

Alternative System Raw material extraction

Waste disposal at C&D site

Reticulated water supply Fossil fuel extraction and processing

Collection/transfer

Collection/transfer

Materials recovery facility Aggregate production Transfer

Concrete reprocessing (Current: manual)

Concrete reprocessing (Future: mechanised)

Reprocessed concrete material

Reprocessed concrete material

Transport to point of use

Transport to point of use

Aggregate material Transfer

Transport to point of use

Landfill

Electricity generation and supply Landfill

Natural gas extraction and supply Reticulated water supply

Generally temporary applications

Fossil fuel extraction and processing

Figure 4 - System boundary for the recycling and alternative systems

3.3.3

System description and boundary

This study aimed to include all unit processes associated with the supply of the functional unit. The system boundary for the recycling and alternative systems is shown in Error! Reference source not found. which describes the unit processes considered, as well as processes excluded from the study. Processes included in Figure 4

are: collection and

transport, materials recovery and sorting, reprocessing, transport and some landfill. The following background input processes are not shown on the diagram but are included within the system boundary:

ACCEPTED MANUSCRIPT

 electricity generation and supply (including supporting supply chains, such as coal extraction)  natural gas extraction and supply  reticulated water supply  fossil fuel extraction and processing (transport fuels) These are resource inputs that are considered generally applicable to a range of the unit processes included in the systems described by Error! Reference source not found.. Excluded from the system boundary are processes associated with human labour and infrastructure, which are assumed to be minor contributions to the environmental impacts investigated.

4

Results

This section presents the results from the interviews (Section 4.1) and LCA (Section 4.2). 4.1

The interviews

The insights gained from the six semi-structured interviews were collated, and key themes relating to concrete recycling pathways, material flows and environmental performance were identified. The findings concluded that the current practices lacked; appropriate construction and demolition waste classifications; delegation; and control of waste flows by private companies. The interview results also confirmed that the reasons behind low recycling rates in Vietnamese C&DW were a lack of material classifications that make waste segregation for recycling difficult, as well as bottlenecks in waste transport due to a lack of coordination amongst C&DW actors. These insights from the interviews are discussed in much greater detail in Lockrey et al. (2016). Moreover, results helped inform the establishment of the LCA system boundary, in particular the current material flow of concrete from C&DW as a gravel replacement in temporary roads and the manual nature of the concrete recycling process. Implications of the themes revealed by interviews are further discussed in Section 0, in terms of how they relate to the environmental performance of concrete derived from C&DW.

4.2

The life cycle benefits of recycling concrete from C&DW

The environmental performance of recycling concrete in Hanoi was explored using LCA, the

ACCEPTED MANUSCRIPT methodology of which is detailed in Section 3.1. The following section provides results on a recycling inventory analysis (Section 4.2.1) of the systems under investigation, and the results of impact assessment of those inventories using streamlined LCA (Section 4.2.2).

4.2.1

Inventory analysis

Inventory analysis is concerned with the collection, analysis and validation of data that quantifies the appropriate inputs and outputs of a product system. Table 1 summarises the inventory for the current recycling and alternative system. The reason that the inventories for the current recycling and alternative system can be considered the same is that both scenarios track the process of aggregate production and eventually disposal (to landfill or through osmosis to the biosphere). Table 2 summarises the inventory for one future recycling system, and Table 3 summarises the inventory for a second future recycling system. These propositions for recycling systems are mechanised and automated plants. The inventories for these scenarios were sourced from two Australian based studies completed by the Centre for Design at RMIT University, for two different industry partners. The reason to include two systems is to produce an average result based on the two studies, and demonstrate that differences in mechanisation and efficiency can affect absolute results. When sourcing generic local materials, processing and end of life data, all attempts to adapt data for Vietnam conditions have been made, based on existing LCI data from the Australian Unit Process Life Cycle Inventory (AUPLCI), ecoinvent 2.2, European data Life Cycle Database (ELCD), and previous Centre for Design at RMIT University studies (Carre et al., 2009, Grant and James, 2005, Grant et al., 2001, Grant et al., 2003). Adapting these data included incorporating the Vietnamese electricity grid into unit processes used from LCIs, as well as including aspects of the Vietnamese system revealed from interviews. Electricity production and distribution data for Vietnam is based on existing data from the IEA. All energy and fuel sources are for European conditions (i.e., energy from coal, gas, wood, etc.), apart from transport which is from AUPLCI (Australian Process Life Cycle Inventory http://alcas.asn.au/AusLCI/), however all are assumed similar to Vietnamese technological conditions.

ACCEPTED MANUSCRIPT Table 1 - Life cycle inventory for the current recycling (manual crushing) and alternative systems (gravel production) Item

Life cycle

Material and processing; transportation; end of life

Region and

stage

data source/s and assumptions

adjustments

Average of: - Aggregate 1: 1.5 t of crushed stone 16/32, open pit mining, production mix, at plant, undried from

Gravel

Material and

production

processing;

European data Life Cycle Database, adapted for

European data

Vietnam electricity

with electricity

- Aggregate 2: 1.5 t of gravel, crushed, at site and disposed and gravel mining adapted from

adapted for Vietnam

ecoinvent 2.2, adapted for Vietnam electricity - Aggregate 3: 1.5 t of gravel, crushed, from an internal CfD&S study adapted for Vietnam electricity

Transfer

Transportation

Sorting, processing and

Australian data,

articulated truck from mine to site, from Australian

but globally

Unit Process Life Cycle Inventory (AUPLCI)

relevant

Handling of waste of 1.5 t of gravel to landfill and End of life

landfill of inert material in landfill from ecoinvent 2.2, adapted to Vietnam electricity

disposal Electricity

Transport of 1.5 t of gravel 50 kilometres (km) by

All stages

Vietnam electricity grid, from the International Energy Agency (IEA)

European data with electricity adapted for Vietnam Vietnam

Table 2. - Life cycle inventory for future recycling system 1 (automated concrete crushing) Item

Life cycle

Material and processing; transportation; end of life

Region and

stage

data source/s and assumptions

adjustments

1.5 t processed at automated concrete recycling plant model - from internal industry study at Gravel

Material and

production

processing;

Centre for Design, RMIT University (Crossin,

Australian data

2012b)

with electricity

- Based on plant operating in Victoria, Australia - Outputs of recycled aggregate and recovered steel reinforcement allocated by mass

adapted for Vietnam

ACCEPTED MANUSCRIPT Item

Transfer

Life cycle

Material and processing; transportation; end of life

Region and

stage

data source/s and assumptions

adjustments

Transportation

and

gravel to landfill and landfill of inert material in End of life

landfill from ecoinvent 2.2, adapted to Vietnam electricity. Avoided dismantling impacts cut-off /

disposal Electricity

truck from mine to site, from AUPLCI Avoided impacts from handling of waste of 1.5 t of

Sorting, processing

Transport of 1.5 t of gravel 50 km by articulated

ascribed to impacts of building All stages

Vietnam electricity grid, from the IEA

Australian data, but globally relevant European data with electricity adapted for Vietnam Vietnam

Table 3 - Life cycle inventory for future recycling system 2 (automated concrete crushing) Item

Life cycle

Material and processing; transportation; end of life

Region and

stage

data source/s and assumptions

adjustments

1.5 t processed at automated concrete recycling plant, crushed, at site: - Internal industry study at Centre for Design, Gravel

Material and

RMIT University (Carre and Rouwette, 2008)

production

processing;

- Based on plant operating in Victoria, Australia

Australian data with electricity adapted for Vietnam

- Outputs of recycled aggregate using system expansion; credits for avoided steel with steel reprocessing impacts included

Transfer

Transportation

and

landfill and landfill of inert material in landfill from End of life

ecoinvent 2.2, adapted to Vietnam electricity. Avoided dismantling impacts cut-off/ ascribed to

disposal Electricity

truck from mine to site, from AUPLCI Avoided handling of waste of 1.5 t of gravel to

Sorting, processing

Transport of 1.5 t of gravel 50 km by articulated

impacts of building All stages

Vietnam electricity grid, from the IEA

Australian data, but globally relevant European data with electricity adapted for Vietnam Vietnam

ACCEPTED MANUSCRIPT

4.2.2

Impact assessment

The primary aim of an impact assessment is to identify and establish a link between a life cycle, and the potential environmental impacts associated with it. Section 4.2.2 documents the impacts associated with the inventory results listed in Section 4.2.1. The results for each current and future recycling system environmental impacts are tabulated in Table 4.

Table 4 - Recycling system impacts, per m3 of recycled concrete Impact category

Units

Average current

Future recycling

Future recycling

recycling system

system 1

system 2

impact

impact

impact

Global warming

kg CO2 eq

-32.30

-15.92

-30.73

Eutrophication

kg PO4 eq

-0.047

-0.013

-0.022

Solid waste

kg

-24.55

-0.002

-1.28

Photochemical oxidation

kg C2H4 eq

-0.0080

-0.0034

-0.0055

Notes: Impacts are indicated with a - ve number

Based on the systems described by Figure 3, the net benefit of the current (manual) and each future recycling option (mechanised plants) for each impact category is graphed in Figure 5 to Figure 8. To determine any net benefit (or impact) they are compared to the alternate recycling system (aggregate production). Net benefits compared to the current recycling system are indicated with a positive (+ve) number, and net impacts are indicated with a negative (-ve) number.

ACCEPTED MANUSCRIPT 18.00 16.00 14.00

kg CO2-eq

12.00 10.00 8.00 6.00 4.00 2.00 0.00 Result

Average current recycling net benefit 0.00

Future recycling system 1 net benefit 16.38

Future recycling system 2 net benefit 1.57

Average future recycling system 8.98

Figure 5 - Global warming net benefits per m3 of recycled concrete (+ve number indicates a net benefit to recycling)

0.018 0.016 0.014

kg C2H4-eq

0.012 0.010 0.008 0.006 0.004 0.002 0.000 Result

Average current recycling net benefit 0.00

Future recycling system 1 net benefit 0.0046

Future recycling system 2 net benefit 0.0025

Average future recycling system 0.0035

Figure 6 - Photochemical oxidation net benefits per m3 of recycled concrete (+ve number indicates a net benefit to recycling)

ACCEPTED MANUSCRIPT 0.040 0.035 0.030

kg PO4- eq

0.025 0.020 0.015 0.010 0.005 0.000 Result

Average current recycling net benefit 0.00

Future recycling system 1 net benefit 0.034

Future recycling system 2 net benefit 0.025

Average future recycling system 0.030

Figure 7 - Eutrophication net benefits per m3 of recycled concrete (+ve number indicates a net benefit to recycling)

30.00

25.00

20.00

kg

15.00

10.00

5.00

0.00 Result

Average current recycling net benefit 0.00

Future recycling system 1 net benefit 24.55

Future recycling system 2 net benefit 23.28

Average future recycling system 23.91

Figure 8 - Solid waste net benefits per m3 of recycled concrete (+ve number indicates a net benefit to recycling)

ACCEPTED MANUSCRIPT For the two proposed future recycling systems (mechanised plants), as well as the average across the two future systems, Figure 5 to Figure 8 show net environmental benefits exist for all impact categories examined as compared to the current recycling system (greenhouse gas emissions, solid waste, eutrophication and photochemical oxidation). It must be noted that as the current recycling system (manual) is considered the same as the comparison alternative system (aggregate production). Therefore all net benefits for current recycling system equate to zero. This demonstrates the potential opportunity of considering new technology options over current manual practices for Vietnamese concrete recycling as it relates to environmental impact reduction, which is discussed next section. 5

Discussion and conclusion

The interview responses from this study provided ‘on-the-ground’ insights into how concrete waste is handled in the C&DW sector in Hanoi, and the current challenges and constraints for expansion. Interview results are explored in more detail in Lockrey et al. (2016), providing a better understanding of the opportunities for concrete recycling in the sector. Of critical importance is the current status quo, where recycled concrete waste is used in temporary roads (replacing gravel from virgin material production). Here the environmental impacts from processing manually, and a final landfill fate (or after being lost to the biosphere from the original recycled function) are retained. These insights are supported by previous studies where C&DW class D has been used for pavement construction (Silva et al., 2017). In short, manually crushing rock for gravel compared to breaking up concrete manually for temporary roads are inherently the same. As such, there are no net recycling benefits or impacts in a choice either way. There may be impacts or benefits in other life cycle stages, such as material comparison; however this is outside the scope of this study. It is clear that C&DW, and concrete as a major component of this waste, is becoming an indispensable issue not only for Hanoi but for Vietnam more broadly as infrastructure development increases (Manowong and Brockmann, 2010, Kien et al., 2013). Some studies show that these environmental benefits are small relative to that of other materials in C&DW, such as metals (Wang et al., 2017, Grant and James, 2005). However material waste issues remain, in that concrete dominates the C&DW stream by mass (Smith et al., 2011). A major contribution of this study is that it is the first attempt at understanding the system and using LCA to quantify the environmental impacts and benefits of recycling concrete. Avoiding the practice of sending manually crushed concrete waste to applications that lead to landfill or loss to the biosphere has been demonstrated to lead to environmental benefits in Hanoi. A practical contribution of this research therefore is that the C&DW recycling industry can

ACCEPTED MANUSCRIPT better understand the current material flows and where approaches to environmental benefits may lie. Another major contribution is that results show that if concrete was to be recycled in a more organized way; benefits compared to the current recycling practices may be achieved. Results are therefore consistent with other LCA studies investigating a C&DW, in that recycling is beneficial (Wu et al., 2014, Grant and James, 2005). Current manual crushing of concrete waste with picks and hammers has functional benefits for use in temporary applications. However results from this study suggest benefits to using a mechanised plant. If automated concrete crushing technology was utilized to provide better reuse options, environmental savings would result across the board (see Figure 5 to Figure 8). A case for technological advancements in concrete recycling in the C&DW sector is then made. This aligns to a recent study from Liu et al. (2017) found a net benefit using high pressure water jet crushing concrete technology, which could be considered for the Vietnamese context. Benefits are realised then by avoiding landfill (or avoided loss to the biosphere), and leveraging permanent applications such as use in levelling, building foundations, or new building materials. For the latter, new material applications may then become viable in Vietnam, such as those being explored in Spain (Mercader-Moyano et al., 2017). Also, based on interviews (presented in detail previously by Lockrey et al. (2016)), to move in new directions the C&DW sector in Hanoi may need to:

ACCEPTED MANUSCRIPT  Develop clear and consistent C&DW classifications so that C&DW fractions can be segregated for more sophisticated reprocessing.  Establish clear lines of responsibility, and coordinating activities amongst key stakeholder to better facilitate new recycling practices and outcomes.  Promote the benefits of concrete recycling from both an economic and environmental perspective, such as in high value applications.

However stakeholder support, participation and investment in such initiatives would be required, to ensure the C&DW recovery sector could transition to mechanised recycling. Such an approach was also relevant in China, where key champions, capacity building and promoting commercial viability were seen as essential to expanding the C&DW recycling sector (Jin et al., 2017). Likewise, a stakeholder approach could better realise environmental benefits in Hanoi, and more broadly in Vietnam.

C&DW, and concrete as a major component of this waste, is a growing issue (Manowong and Brockmann, 2010, Kien et al., 2013) that Vietnam must address as urban development continues to trend higher. To contribute to activities initiated to address this issue (Thai, 2009), the research in this paper mapped and quantified the environmental performance of recycling concrete in Hanoi. Current concrete waste logistics pathways and material flows in Hanoi were investigated, and from these insights the environmental performance of Vietnam’s existing concrete recycling system was quantified. Different recycling pathways that avoid landfill have been proposed as for positive future environmental outcomes in the Vietnamese context.

Practically, a lot must be done to achieve an ambitious transformation in Vietnamese C&DW recycling. Identifying and exploiting waste opportunities in Vietnam, and other nations developing at a similar speed, is an opportunity. It is hoped better environmental outcomes are delivered by taking advantage of the opportunities that new concrete recycling initiatives provide.

6

Limitations and future research

A key limitation to this study was that although 23 stakeholders were engaged for interviews, only 6 in-depth interviews were conducted (26% response rate). As such the responses do

ACCEPTED MANUSCRIPT not necessarily provide insights that can be generalised across the concrete recycling market. However, these interviews provide preliminary insights containing deep meaning and descriptions about particular issues regarding concrete recycling for each particular context, which will form the basis to develop further research (Brinkmann, 2018). The LCA conducted in this research is a streamlined assessment, guided by ISO 14040:2006 principles. The LCA has not been externally peer reviewed against this ISO standard. The assumptions, limitations and considerations made in regard to the inventory compiled for this LCA, limit the scope of the study. When sourcing generic local materials, processing and end of life data, all attempts to adapt data for Vietnam conditions have been made, based on existing data from life cycle inventories, and previous Centre for Design, RMIT University studies. The adapted Vietnamese data may not reflect actual conditions. The allocation perspective from which the LCA component of this research is compiled is important. LCAs are typically compiled from a largely attributional standpoint, from which the existing impacts of the system are allocated to the unit processes that make up the system. Consequential LCA methodology, as described by Weidema (2003), tracks environmentally relevant physical flows to and from a system that will modify in response to possible changes in the life cycle. A consequential LCA methodology is designed to generate information on the consequences of actions (Weidema, 2003). The difference between the consequential and attributional approach is particularly relevant to the assessment of recycling systems, especially where growth in recycling is the desired outcome. The attributional approach assumes that an increase in recycling will result in environmental impacts that are linearly related to the impacts of the current recycling system. The consequential approach does not assume a linear ‘scaling’ of the existing system, but rather explores shifts of behaviour within the system. Both approaches have their limitations which (Ekvall, 2003) summarises:  Attributional LCA: o

Describes systems only

o

Systems are subjective (allocation, geographical boundaries etc.)

 Consequential LCA: o

Describes consequences only

o

Entails great uncertainty and instability

ACCEPTED MANUSCRIPT

In this study, an attributional approach has been used to characterise the impacts of the existing and alternative recycling system based on the work by Ekvall and Tillman (1997). A consequential approach could be used in future research to determine the impact of policies on the market, seeking to increase recycling rates with new technologies. This study formed insights that now open pathways for research that could tackle concrete waste issues, or explore opportunities that have become apparent. Some of those pathways are described below. Research could target how to better manage relationships and resources in order to eradicate bottlenecks in the management of concrete waste. Part of this research could be aimed at the development of clear and consistent C&DW classifications so that C&DW fractions can be segregated for recycling. Organizational research could also help identify what is needed for this to happen from a stakeholder perspective. A review exploring the best ways to exploit and promote the benefits of concrete recycling, from both an economic and environmental perspective, could be actioned. This could include identifying; opportunities and barriers to higher value concrete waste recycling outcomes; best practice waste management techniques and technological advancements; and financial incentives, for effective and achievable strategies available in the Vietnamese context, and those in other developing nations. Government focused research into the role of agencies and stakeholders could determine what clear lines of responsibility are required for better recycling practices and outcomes. Government policy research could be used to help co-ordinate and support investment in beneficial technology adoption and activities amongst key stakeholders. Finally, more detailed LCA projects quantifying the net benefit of C&DW recycling across Vietnam could more accurately uncover the scale of concrete recycling opportunity. The LCA research could involve the following activities:  Expanding the study to quantify waste flows, including concrete and other major construction material fractions, across the whole of the Hanoi economy. This would provide a picture of the key materials and quantities and enable ‘hot spots’ and areas to focus upon, to be made.  Expanding the mapping of C&DW fractions into other major metropolitan areas in

ACCEPTED MANUSCRIPT Vietnam.  Development of a preliminary LCI database for Vietnam, incorporating electricity grids, freight systems and construction material production (bricks, concrete, steel).  Integrating LCI and LCA data into green building schemes.

It may also be beneficial to expand this research to other developing nations, where rapid expansion of construction and demolition projects is evident. The earlier research is initiated the better, as opportunities may be capitalized upon, and risks to the environment reduced.

Acknowledgements

This research was funded through an internal RMIT University grant. Professor Bob Baulch, Professor Ralph Horne and the Vietnam Research Partnership Support Scheme at RMIT should be acknowledged as key funding contributors to the work.

Thank you also to Phuong Minh Nguyen, who worked on data collection and analysis throughout the research.

Those individuals who participated anonymously in the interviews and shared their knowledge were critical to the development of this paper. Thank you for your time and contributing your expertise.

Finally, thank you to the editors of this special edition that provided the opportunity to progress research initially presented at ISDRS Conference in Lisbon, 2016. In doing so this paper contributed to the theme of the special issue, by rethinking sustainability in questioning old perspectives, and developing new ones.

ACCEPTED MANUSCRIPT 7

References

AECOM 2013. Asia - Construction Outlook 2013. In: AECOM (ed.). Los Angeles, USA: AECOM. ALEX FRASER 2014. Technical Information Sheet - CLASS 4 CRUSHED CONCRETE. In: FRASER, A. (ed.). Laverton North. BAUMANN, H. & TILLMAN, A. M. 2004. The Hitch Hiker's Guide to LCA. An orientation in life cycle assessment methodology and application, External organization. BOSMA, R., ANH, P. & POTTING, J. 2011. Life cycle assessment of intensive striped catfish farming in the Mekong Delta for screening hotspots as input to environmental policy and research agenda. The International Journal of Life Cycle Assessment, 16, 903-915. BRINKMANN, S. 2018. The Interview In: LINCOLN, N. K. D. A. Y. S. (ed.) The Sage handbook of qualitative research. 5th ed.: Sage Publicaitons. CARRE, A., CROSSIN, E. & CLUNE, S. 2015. LCA of Kerbside recycling in Victoria. RMIT University, Melbourne. CARRE, A., JONES, I., BONTINCK, P.-A. & HAYES, G. D.-M. 2009. Extended Environmental Benefits of Recycling (EEBR) Project. Melbourne: RMIT University. CARRE, A. & ROUWETTE, R. 2008. Life cycle comparison of crushed concrete aggregate with traditionally quarried stone aggregate. Melbourne, Australia: RMIT University, for Australian industry partner CHEN, C., HABERT, G., BOUZIDI, Y., JULLIEN, A. & VENTURA, A. 2010. LCA allocation procedure used as an incitative method for waste recycling: An application to mineral additions in concrete. Resources, Conservation and Recycling, 54, 1231-1240. COELHO, A. & DE BRITO, J. 2013. Environmental analysis of a construction and demolition waste recycling plant in Portugal - Part II: environmental sensitivity analysis. Waste Management, 33, 147-161. CROSSIN, E. 2012a. Comparative Life Cycle Assessment of Concrete blends. Report for Grocon (Victoria Street) Pty Ltd. Melbourne: RMIT University. Centre for Design. CROSSIN, E. 2012b. Life cycle comparison of concrete blends. Melbourne, Australia: RMIT University, for Australian industry partner CROSSIN, E. 2015. The greenhouse gas implications of using ground granulated blast furnace slag as a cement substitute. Journal of Cleaner Production, 95, 101-108. CURRAN, M. A. 1993. Broad-based environmental life cycle assessment. Environmental Science & Technology, 27, 430-436. EKVALL, T. Attributional and consequential LCI modelling (presentation). InLCA/LCM 2003, 2003 Seattle, Washington. American Center for Life Cycle Assessment. EKVALL, T. & TILLMAN, A. M. 1997. Open-loop recycling: Criteria for allocation procedures. International Journal of Life Cycle Assessment, 2, 155-162. GRANT, T. & JAMES, K. 2005. Life Cycle Impact Data for Resource Recovery from Commercial and Industrial and Construction and Demolition Waste in Victoria Melbourne: Centre for Design, RMIT University. GRANT, T., JAMES, K., LUNDIE, S. & SONNEVELD, K. 2001. Stage 2 Report for Life Cycle Assessment for Paper and Packaging Waste Management Scenarios in Victoria. GRANT, T., JAMES, K. & PARTL, H. 2003. Life Cycle Assessment of Waste and Resource Recovery Options (including energy from waste) - Final Report for EcoRecycle Victoria. Melbourne, Victoria: Centre for Design at RMIT University (www.cfd.rmit.edu.au). HAO, J., HILLS, M. & TAM, W. 2010. Dynamic modelling of construction and demolition waste management processes An empirical study in Shenzhen China. Engineering, Construction and Architectural Management, 17, 476-492. HOMÄKI, K., NIELSEN, P. H., SATHASIVAN, A. & BOHE, E. L. J. 2003. Life cycle assessment and environmental improvement of residential and drinking water supply systems in Hanoi, Vietnam. International Journal of Sustainable Development & World Ecology, 10, 27-42. HOTTA, Y. The 3Rs and Sustainable Resource Circulation. Progress and Research Activties in IGES. Global Partnership on Waste Management: Working Group Meeting, December 5 and 6 2011 Vienna, Austria. Institute for Global Environmental Strategies. HUSSIN, J., ABDUL RAHMAN, I. & HAMEED MEMON, A. 2013. The way forward in sustainable construction: issues and challenges. International Journal of Advances in Applied Sciences, 2, 15-24. HUYSVELD, S., SCHAUBROECK, T., DE MEESTER, S., SORGELOOS, P., VAN LANGENHOVE, H., VAN LINDEN, V. & DEWULF, J. 2013. Resource use analysis of Pangasius aquaculture in the Mekong Delta in Vietnam using Exergetic Life Cycle Assessment. Journal of Cleaner

ACCEPTED MANUSCRIPT Production, 51, 225-233. INTERNATIONAL ORGANIZATION FOR STANDARDIZATION 2006b. Environmental Management Life cycle assessment - Requirements and guidelines. Geneva: International Organisation for Standardisation. JIN, R., LI, B., ZHOU, T., WANATOWSKI, D. & PIROOZFAR, P. 2017. An empirical study of perceptions towards construction and demolition waste recycling and reuse in China. Resources, Conservation and Recycling 126, 86-98. KIEN, T. T., THANH, L. T. & LU, P. V. Recycling construction demolition waste in the world and in Vietnam. The International Conference on Sustainable Built Environment for Now and the Future, 2013 Hanoi. KLÖPFFER, W. 1997. Life cycle assessment. . Environmental Science and Pollution Research, 4, 223-228. KLUTS, I. N., POTTING, J., BOSMA, R. H., PHONG, L. T. & UDO, H. M. J. 2012. Environmental comparison of intensive and integrated agriculture–aquaculture systems for striped catfish production in the Mekong Delta, Vietnam, based on two existing case studies using life cycle assessment. Reviews in Aquaculture, 4, 195-208. KNOERI, C., SANYÉ-MENGUAL, E. & ALTHAUS, H.-J. 2013. Comparative LCA of recycled and conventional concrete for structural applications. The International Journal of Life Cycle Assessment, 18, 909-918. KURAD, R., SILVESTRE, J. D., DE BRITO, J. & AHMED, H. 2017. Effect of incorporation of high volume of recycled concrete aggregates and fly ash on the strength and global warming potential of concrete. Journal of Cleaner Production, 166, 485-502. LING, F. Y. & NGUYEN, D. S. A. 2013. Strategies for construction waste management in Ho Chi Minh City, Vietnam. Built Environment Project and Asset Management, 3, 141 - 156. LIU, J., WANG, M. & ZHANG, D. Numerical simulation of high pressure water jet impacting concrete. AIP Conference Proceedings, 2017. AIP Publishing, 020075. LOCKREY, S., NGUYEN, H., CROSSIN, E. & VERGHESE, K. 2016. Recycling the Construction and Demolition Waste in Vietnam: Opportunities and Challenges in Practice. Journal of Cleaner Production, 133, 757–766. MANOWONG, E. & BROCKMANN, C. Construction Waste Management in Newly Industrialized Countries. CIB Working Commission, W107 - Construction in Developing Countries, Papers and Postgraduate Papers from the Special Track, 2010 Salford Quays. MARINKOVIĆ, S., RADONJANIN, V., MALEŠEV, M. & IGNJATOVIĆ, I. 2010. Comparative environmental assessment of natural and recycled aggregate concrete. Waste Management, 30, 2255-2264. MERCADER-MOYANO, P., GARCÍA-DE-LA-CRUZ, M. V. R. & YAJNES, M. E. 2017. Development of New Eco-Efficient Cement-Based Construction Materials and Recycled Fine Aggregates and EPS from CDW. The Open Construction and Building Technology Journal 11, 381-394. MERCANTE, I. T., BOVEA, M. D., IBÁÑEZ-FORÉS, V. & ARENA, A. P. 2012. Life cycle assessment of construction and demolition waste management systems: a Spanish case study. The International Journal of Life Cycle Assessment, 17, 232-241. PHONG, L. T., DE BOER, I. J. M. & UDO, H. M. J. 2011. Life cycle assessment of food production in integrated agriculture–aquaculture systems of the Mekong Delta. Livestock Science, 139, 8090. R. HEIJUNGS, J.B. GUINÉE, G. HUPPES, R.M. LANKREIJER, H.A. UDO DE HAES, A. WEGENER SLEESWIJK, A.M.M. ANSEMS, P.G. EGGELS, R. VAN DUIN & GOEDE, H. P. D. 1992. Environmental life cycle assessment of products: Backgrounds and environmental life cycle assessment of products–Guide Leiden, Netherlands: CML, TNO, B&G. SILVA, R. V., DE BRITO, J. & DHIR, R. K. 2017. Availability and processing of recycled aggregates within the construction and demolition supply chain: A review. Journal of Cleaner Production, 143, 598-614. SIMETRIC. 2014. Density of materials - Bulk Materials [Online]. SImetric. Available: http://www.simetric.co.uk/si_materials.htm. SMITH, K., O'FARRELL, K. & BRINDLEY, F. 2011. Waste and Recycling in Australia 2011. Sydney: Hyder, DSEWPC. TAM, V., SHEN, L. & TAM, C. 2007. Assessing the levels of material wastage affected by subcontracting relationships and projects types with their correlations. Building and Environment, 42, 1471-7. THAI, N. 2009. Hazardous industrial waste management in Vietnam: current status and future direction. Journal of Material Cycles and Waste Management, 11, 258-262.

ACCEPTED MANUSCRIPT VGBC 2013. Is there a future fror green buildings in Vietnam? : Solidiance, for Vietnam Green Building Council. WANG, J., WU, H., DUAN, H., ZILLANTE, G., ZUO, J. & YUAN, H. 2017. Combining Life Cycle Assessment and Building Information Modelling to account for carbon emission of building demolition waste: a case study. Journal of Cleaner Production. WASTE MANAGEMENT AND ENVIRONMENT IMPROVEMENT DEPARTMENT 2013. Development of National Program on Reduce, Reuse, Recycle. Fourth Regional 3R Forum in Asia. WEIDEMA, B. 2003. Environmental Project No. 863 - Market Information in Life Cycle Assessment, Denmark, Danish Environmental Protection Agency. WOODSIDE, A. 2010. Bridging the chasm between survey and case study research: Research methods for achieving generalization, accuracy, and complexity. Industrial Marketing Management, 39, 64-75. WORLD BANK, MONRE & CIDA 2004. Vietnam Environment Monitor 2004. Solid Waste. World Bank, Ministry of Environment and Natural Resources (MONRE), Canadian International Development Agency (CIDA). WU, P., XIA, B. & ZHAO, X. 2014. The importance of use and end-of-life phases to the life cycle greenhouse gas (GHG) emissions of concrete – A review. Renewable and Sustainable Energy Reviews, 37, 360-369.